Blue Screen RE Error Code

I am not even sure if this a windows issue however windows claimed it did send the system to this screen with the error message outlining vaguely what it is protecting the system from by crashing and not being damaged.
What I am attempting to do is install the final 256M DIMM modules on a Biostar M5SSA for a total of 768M, which is its max for this motherboard.  I have increase the memory on this machine previously and had no problems.  So slot 0 has 256M, slot 1 has 256M but each time I put the final module in I get the blue screen of death with the following messages, leaving out the boilerplate warning stuff it states:

IRQL_NOT_LESS_OR_ EQUAL
*** STOP:
0x0000000A (0x00000004, 0x00000002, 0x00000000, 0x8050E710)
Beginning dump of physical memory.
Physical memory dump complete.

I will certainly appreciate any help or redirection on this frustrating hurdle.

Chris
chrisw@pacific.net